Update on Mars' atmosphere, Media briefing on NASA Jan 15th Options

[Stu]

Interesting...

http://www.spaceref.com/news/viewpr.html?pid=27336

[dvandorn]

While there will be an awful lot of study and theorizing about the source(s) of the observed methane, and an awful lot of modeling of said sources, I think perhaps one of the things that needs to be really pinned down hard before those models gain any credibility is the volume of methane being released over time. I know they have some figures right now, but they're only showing plumes in three small-ish areas of Mars. Are those the *only* sources? Or have we not looked closely enough at the rest of the planet to find others?

Once you know how much you're releasing, you can project total release levels over much longer periods, like millions and billions of years. If it turns out, for example, that the current release rate (which is really very low on a planetary scale, I believe) would over a billion years require that a methane ocean has to have been sealed up and slowly leaked out over that period, that makes the ancient origin theory unlikely. If it would only require a few thousand tons of clathrated methane, spread out over only perhaps several thousand total cubic kilometers (a very small percentage of Mars' upper crust), then the ancient origin theory looks a lot better.

If the release volume, as projected against a variety of assumption sets, seems to require constant (if very low-level) production of methane over time, then the various other theories gain more ground.

(And yes, I know that release rates have probably changed over time. You can plug such changes into the release-over-time models, if you wish, as long as your changes are in some way supported by actual data.)

One thing that was just mentioned at the press conference (I recorded it on my DVR and am watching it now) is the possibility that there might be a layer of permafrost under the entire Martian crust, even the equatorial plains. Do we have any real evidence of this from either of the radar experiments? Or is this simply another model they're tossing around?

More and more, I want to get heat flow data from Mars. An awful lot of what's actually happening under the first few km of Mars' crust depends on the temperature regimes of its crust, mantle and core. We have very little idea of how much remanent heat may yet be contained within the planet, how heterogenous (or not) its distribution might be, and very specifically at what locations and depths water (and other things, like methane) might exist as solids, liquids and even gasses.

-the other Doug

[HughFromAlice]

While there will be an awful lot of study and theorizing about the source(s) of the observed methane, and an awful lot of modeling of said sources, I think perhaps one of the things that needs to be really pinned down hard before those models gain any credibility is the volume of methane being released over time......... More and more, I want to get heat flow data from Mars. the other Doug

"Other" Doug - I think you have raised interesting points.

My interest is in what the next generation of Mars orbiters and ground based craft should be looking at. Mumma noted that our past focus on following geology/minerals lead to the choice of Meridiani as the landing site for Opportunity and to the subsequent 'cornucopia of information' culminating with evidence of standing water on Mars. Now we need to target missions to investigate active areas.

He was also at pains to point out that his data analysis and control of instrumental artifacts was 'unassailable for any point of view"!! Is there anyone in UMSF really up in spectroscopy that has read Mumma's recent Science paper and would like to comment on the algorithms/techniques he used? Would be interesting to hear from an expert.

I thought a lot of really key things in this press briefing came out towards the end as the panel loosened up after a few questions from the audience.

Villanueva noted that a lot more can be learned from going back to their (massive) data sets (and CRISM data sets for gen mineralogy) in the light of these results. Particularly checking how old the water is that has been detected along with CH4. Old production - new release or new production - new release? He then commented that they are doing this and will submit a paper for publication soon. Also Mumma made allusions to more papers to come soon - such as looking at seasonal repeatability.

Mumma pointed out that if 'bio' is near the surface then it should be using water that is in contact with the atmospheric escape and so will have a high D content. But water below permafrost is ancient and likely to be much lower in D. Then to throw the cat among the pigeons, Pratt pointed out that we know very little about D/H ratios due to radiolytic splitting of water. (So we need to do more research here on earth before anything else!!).

She continued that CH4 and D/H ratios would not be enough for absolute proof anyway - we would need to positively identify a suite of biomarker gases like turpines etc. etc. If we can't do this, we will need to drill down and pump water out! She pointed out that to verify life that exists in thin films deep underground on Earth it is necessary to filter 100,000s of litres of water and then either visually identify the life forms or grow them! We'll need a mighty spacecraft to drill and pump!!! Mars Science Laboratory might get very very lucky and sample concentrated gases at a release point which would - at least - give us strong indicators.

Sushil Atreya also commented that we need to look on the ground for heavy hydrocarbons. If ethane and propane were found then geo source would be more likely. Mumma said that they have began to look at this in 2006 and that there will be a publication later in the year. Another one?

For me the most interesting comments of all came from Lisa Pratt. She pointed out that it is much easier to make a living consuming methane than excreting it. There is an enormous amount of sulphate on the surface of Mars. Sulphate reduction coupled to methane oxidation starts to look like a very attractive proposition. On Earth, this metabolism in one of the most ancient ones. So if methane is coming out in focused areas then it gives us a bull's eye to go in and search.

Now that's what I call a really exciting hook to get priority funding for new missions to Mars ---- despite my fascination with Titan (especially) and Europa!!! After all, if that wonderful memorandum of mammary masterpieces - the UK paper 'The Sun' - found it worthwhile to go to the trouble of making a major scoop on a Mars story for its readers, then the pollies might actually see a few votes in it!!!

[silylene]

"Other" Doug - I think you have raised interesting points.
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He was also at pains to point out that his data analysis and control of instrumental artifacts was 'unassailable for any point of view"!! Is there anyone in UMSF really up in spectroscopy that has read Mumma's recent Science paper and would like to comment on the algorithms/techniques he used? Would be interesting to hear from an expert.
...

I'll read it hopefully today and report back my thoughts. (I am a PhD polymer photochemist).